I bought a pair of used stirrup leathers, and the seller threw in a pair of schooling-quality stirrups. They are pretty beat up and so scruffy that I'm worried they might scratch the saddle (when put up for longe-line work, etc.). Is there anything that can be done? Some sandpaper? A cleaner of some sort? I realize stirrups aren't terribly expensive and I could just replace them, but for around the barn maybe they are worth saving.